Compositions for oil recovery and methods of using same

ABSTRACT

A method of removing bitumen from tar sands comprising contacting the tar sands with a first mixture comprising a petroleum distillate and an oxygenated solvent, and recovering a second mixture comprising (a) at least a portion of the petroleum distillate and oxygenated solvent from the first mixture, (b) bitumen and (c) sand having a reduced amount of bitumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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REFERENCE TO A MICROFICHE APPENDIX

Not applicable

FIELD

The present disclosure relates to oil recovery processes. More specifically, the present disclosure relates to methods of treating tar sands to remove bitumen.

BACKGROUND

Tar sands deposits are found throughout the world and are a potentially enormous oil resource. The largest tar sands deposits are found in Alberta (Canada) and Venezuela while smaller deposits can be found in Siberia (Russia), Saudi Arabia and other Middle-Eastern countries, and Utah in the United States. The current methodologies for recovering oil from tar sands typically require large economic and energetic expenditures. For example, the processes may require the use of heated water and/or the consumption of a large quantity of water to recover the oil, which in itself may have a negative environmental impact. Thus, it would be desirable to develop improved methods for the recovery of oil from tar sands.

SUMMARY

Disclosed herein is a method of removing bitumen from tar sands comprising contacting the tar sands with a first mixture comprising a petroleum distillate and an oxygenated solvent, and recovering a second mixture comprising (a) at least a portion of the petroleum distillate and oxygenated solvent from the first mixture, (b) bitumen and (c) sand having a reduced amount of bitumen.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

FIG. 1 is a schematic of a reactor system.

FIG. 2 is a schematic of a membrane separation unit.

DETAILED DESCRIPTION

It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

Disclosed herein are compositions for recovering bitumen from tar sands and methods of using same. In an embodiment, the method comprises contacting tar sands with an oil recovery mixture. The compositions and methods are described in more detail later herein.

In an embodiment, a method of recovering bitumen from tar sands is described. Such tar sands are known to one of ordinary skill in the art and may be referred to also as bituminous sands, sands containing bitumen, oil sands, and/or heavy oil sands. For simplicity, hereinafter these materials will be referred to as tar sands. Tar sands may be found throughout the world, but most of the world's tar sands reserves are in Alberta/Canada (known as the Athabasca oil sands) and Venezuela (known as the Orinoco oil belt). Tar sands are comprised primarily of clay, sands, water, and bitumen. Bitumen (also known as tar, asphalt, native asphalt, gunk, hydrocarbon, heavy oil, and/or extra heavy oil) is a semisolid form of oil composed primarily of highly condensed polycyclic aromatic hydrocarbons. Bitumen may be further characterized as a material that does not flow at normal temperatures and pressure and/or without dilution.

In an embodiment, the bitumen has an American Petroleum Institute (API) gravity of less than about 10° as determined in accordance with ASTM D1298 and may also be referred to as heavy oil. The API gravity is a measure of how heavy or light a petroleum liquid is compared to water. If its API gravity is greater than 10°, it is lighter and floats on water; if less than 10°, it is heavier and sinks. Bitumen may also be characterized as having a dynamic viscosity from about 0.2 Pa·S to about 1000 Pa·S, alternatively from about 1 Pa·S to about 500 Pa·S, alternatively from about 10 Pa·S to about 400 Pa·S, as determined in accordance with ASTM D445. Viscosity is a measure of the resistance of a fluid to deform under shear stress which describes a fluid's internal resistance to flow and may be thought of as a measure of fluid friction. In an embodiment, the bitumen may have an API gravity of 8° and a viscosity of about 5 Pa·S at 50° C., such as for example bitumen obtained from the Athabasca oil sands. In another embodiment, the bitumen may have an API gravity of 8° with viscosity of about 10³ Pa·S at 50° C., such as for example bitumen obtained from the Orinoco oil belt.

In an embodiment, a method for the recovery of oil from tar sands may comprise contacting tar sands with an oil recovery mixture (ORM) comprising at least one petroleum distillate, at least one oxygenated solvent, and optionally one or more surfactants. The petroleum distillate may comprise a hydrocarbon fraction, alternatively a hydrocarbon fraction comprising compounds having from about 4 to about 60 carbon atoms, or from about 4 to about 21 carbon atoms, or from about 8 to about 10 carbon atoms. In an embodiment, the petroleum distillate may comprise a hydrocarbon fraction having a true vapor pressure of equal to or greater than 1 psia as determined in accordance with ASTM D2889-95a(2000). True vapor pressure refers to the pressure of the vapor in equilibrium with the liquid at 100° F. In another embodiment, the hydrocarbon fraction may comprise a hydrocarbon fraction having a Reid vapor pressure of equal to or greater than 4 psia as determined in accordance with ASTM D323-99a. Reid vapor pressure is the pressure exerted by the vapors released from any material at a given controlled temperature when enclosed in a laboratory vapor tight vessel. In an embodiment, the petroleum distillate comprises diesel. Diesel is a hydrocarbon mixture, which may be obtained for example by fractional distillation of crude. Suitable diesel fuel oils are described in ASTM D 975-88, the disclosure of which is incorporated herein by reference. Diesel may also be developed and not derived from petroleum. Examples of suitable diesel developed and not derived from petroleum include for example and without limitation biodiesel, alternatively biomass to liquid (BTL) diesel, alternatively gas to liquid diesel (GTL). In an embodiment, the ORM may comprise from about 90% to about 2% diesel, alternatively from about 80% to about 20% diesel, alternatively from about 70% to about 30% diesel by volume.

In an embodiment, the oxygenated solvent comprises an alcohol ether, a glycol ether, or combinations thereof. Examples of suitable glycol ethers include without limitation ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, diethylene glycol butyl ether, diethylene glycol ethyl ether, ethylene glycol monobutyl ether; or combinations thereof. In an embodiment, the ORM may comprise from about 10% to about 98% oxygenated solvent, alternatively from about 20 to about 80% oxygenated solvent, alternatively from about 30 to about 70% oxygenated solvent by volume.

In an embodiment, the ORM may further comprise a surfactant. An example of a suitable surfactant is GLUCOPON 600 APG which is an alkyl polyglycoside commercially available from Cognis. The surfactant may be present in any amount effective to reduce surface tension or alternatively the surfactant may be present in an amount of from about 0.5% to about 1% by volume of composition.

In an embodiment, tar sands may be contacted with the ORM using any method known to one of ordinary skill in the art, for example by contacting the components in one or more reaction or contacting zones. Alternatively, a method of recovering bitumen from tar sands may employ a reactor system comprising one or more reactor types. As used herein, the term reactor, reactor zone, reactor system, and the like refer to any vessel, container, or unit wherein a user desired process occurs and wherein the process may comprise any number and/or type of interactions between the components (e.g. physical, chemical, etc.).

An embodiment of a reactor system for use in recovery process is schematized in FIG. 1. While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the figures and will herein be described in detail. It is to be understood, however, that the figures and detailed description thereto are not intended to limit the disclosure to the particular form disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

Referring to FIG. 1, the reactor system 100 comprises an extraction reactor 110 coupled to and in fluid communication with separation reactor 150 via flowline 125 which in turn is in fluid communication with a conversion reactor 165 via flowline 160. The extraction reactor 110 may be coupled to and in fluid communication with an attrition scrubber 180 via flowline 115 which is disposed downstream of the reactor 110. The attrition scrubber 180 is upstream of and in fluid communication with a washing tank 130 via flowline 185. The reactor system may comprise additional devices (not shown) such as heaters/coolers, pumps, centrifuge units, drying units, process controllers, and the like as desired to meet the needs of the process.

Referring to FIG. 1, two feed streams may be introduced to extraction reactor 110, a tar sands feed stream via flowline 105 and an ORM feed stream via flowline 120, whereby all or a portion of the bitumen is removed from the tar sands by the ORM. In an embodiment, the tar sands and the ORM components may be fed through independent feedlines and mixed in situ in the reactor, as depicted in FIG. 1. The tar sands and the ORM components may be combined and introduced to extraction reactor 110 using any other method known to one of ordinary skill in the art. For example, the tar sands and the ORM components may be premixed in the feedline before entering the reactor. The premixing may be designed to produce certain characteristics (e.g. homogeneity) and as such the premixing conditions (e.g., time period, agitation methods, etc) may be chosen by one of ordinary skill in the art to meet the needs of the process. In another example (not shown), the tar sands and the ORM components may also be stored in separate storage units, and premixed in a mixing unit before being feed to the extraction reactor 110.

Referring again to FIG. 1, in an embodiment, the extraction reactor 110 comprises a counter current flow reactor such as for example a liquids-solids counter current flow extraction system. Contacting of the two feed streams in the counter current flow reactor may be carried out under conditions suitable to maximize the removal and recovery of bitumen from the tar sands. Herein the use of a material such as the ORM to affect the recovery of bitumen from tar sands will be termed chemically cleaning or chemically treating the material. For example, the rate at which the two streams are introduced to the reactor and the reactor temperature may affect the amount of bitumen recovered. Such reactor conditions may be adjusted by one of ordinary skill in the art. After contacting of said feed streams, two effluent streams may exit the extraction reactor 110, a chemically cleaned sands (CCS) stream via flowline 115 and an ORM/bitumen mixture stream via flowline 125. In an alternative embodiment the effluent may comprise a single stream comprising CCS, ORM, and bitumen that may be conveyed to one or more devices designed to separate the effluent into at least two components. In an embodiment, the device is a gravity separation device wherein the CCS may be removed from the bottom of the device while the ORM and bitumen may be removed from an upper portion of the device. Processing of the separated components may then be carried out as is described in more detail later herein.

In an alternative embodiment, extraction reactor 110 comprises a membrane separation unit. The membrane separation unit may take any suitable shape such as for example a tube, hollow fiber, flat sheet, spiral wound or combinations thereof. The membrane separation unit may comprise a porous membrane that acts as a filter to allow liquid substance to pass through while retaining solid substance. FIG. 2 illustrates an embodiment of a membrane separation unit. Referring to FIG. 2, the membrane separation unit 200 comprises a porous membrane tube 210, a container 230, two feed streams 205 and 220, and two effluent streams 215 and 225. The porous membrane may be comprised of any material compatible with the components of the disclosed process. For example, the porous membrane may be comprised of inorganic ceramic materials (e.g., alumina, titania, zirconia oxides, silicon carbide, glass, etc); organic polymeric materials (e.g., polyalphaolefins, polyaryletherketones, polybutenes, nylons or polyamides, polycarbonates, thermoplastic polyesters, etc); or combinations thereof. The two feed streams, a tar sands feed stream and an ORM feed stream may be introduced to the porous membrane 210 via flowlines 205 and 220 respectively wherein the streams are contacted under conditions suitable for the recovery of bitumen. The tar sands and the ORM components may be premixed as described previously herein. The ORM when contacted with the tar sands and may effect the removal of at least a portion of the bitumen to produce an ORM/bitumen mixture and CCS. At least a portion of the ORM/bitumen mixture may pass through the membrane 210 and be collected in the container 230. Two effluent streams, one comprising a CCS may exit the membrane tube 210 via flowline 215 and a second comprising the ORM/bitumen mixture may exit container 230 via flowline 225. Both effluents may be further processed as described herein.

Referring again to FIG. 1, the CCS that is the effluent from extraction reactor 110 via flowline 115 may exit the reactor system with or without further processing. In an embodiment, the CCS stream may exit extraction reactor 110 via flowline 115 and enter an attrition scrubber 180, where it may be contacted with propellers and/or impellers that function to physically scrub and/or polish the CCS under conditions suitable for the removal of additional bitumen. The CCS after having been physically cleaned is hereinafter referred to as the chemically and physically cleaned sand (CPCS) and may exit attrition scrubber 180 and may or may not be subjected to further processing. In an embodiment, the CPCS may exit attrition scrubber 180 via flowline 185, and be fed to washing tank 130 where it may be contacted with a residual recovery cleaning solvent (RRS) that enters washing tank 130 through flowline 140. The contacting of the CPCS with the RRS may allow for additional bitumen recovery. Examples of suitable RRS include without limitation diesel, water, or aliphatic hydrocarbons. The CPCS after having been contacted with an RRS is hereinafter referred to as low bitumen sands (LBS). The term LBS is meant to indicate the amount of bitumen on the sands is reduced relative to the tar sands introduced to the reactor system. The LBS may exit the washing tank 130 through flowline 135. In some embodiments, the RRS may be recycled and reintroduced to washing tank 130 via flowline 145.

The ORM/bitumen mixture that is recovered from extraction reactor 110 may be further processed to recover the bitumen. In an embodiment, the ORM bitumen mixture may exit the extraction reactor 110 via flowline 125 and be introduced to separation reactor 150 which may function to separate the components of the mixture. The separation reactor may affect the separation of ORM and bitumen via distillation, flashing, centrifugation, settling, stratification, skimming, or any other means known to one of ordinary skill in the art. The ORM when separated from the bitumen in separation reactor 150 may exit the reactor via flowline 155 and be recycled to extraction reactor 110.

The bitumen when separated from the ORM may exit separation reactor 150 via flowline 160 and be introduced to a conversion reactor 165 where it may be converted to a lighter petroleum product. Herein a lighter petroleum product refers to a petroleum product having an API gravity of greater than about 10°. Methods and devices for the conversion of bitumen to a lighter petroleum product are known to one of ordinary skill in the art. For example, conversion reactor 165 may comprise a function to carry out a cracking process. The lighter petroleum product effluent from conversion reactor 165 may exit via flowline 175 where it may be used without further processing. A distillate stream may exit the conversion reactor 165 via flowline 170 and be recycled and fed back to extraction reactor 110.

In an embodiment, the contacting of an ORM and tar sands as disclosed herein may result in a reduced environmental impact and improvements in the overall process economics for bitumen recovery from tar sands when compared to conventional methods. The compositions and methods disclosed herein may result in a bitumen recovery of equal to or greater than about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 96, 97, 98, or 99 weight % of bitumen from the tar sand.

EXAMPLES

The invention having been generally described, the following examples are given as particular embodiments of the invention and to demonstrate the practice and advantages thereof. It is understood that the examples are given by way of illustration and are not intended to limit the specification of the claims to follow in any manner.

Qualitative, quantitative, and comparative experiments were conducted using a combination of chemical and heat treatment to recover bitumen from tar sands. Tar sands, obtained from Canada, were subjected to several mixtures and/or heat treatments. The detailed procedures and results are described in this section. The petroleum distillate used was Orfom™ SX-12 solvent extraction diluent and was used as received. The diesel fuel was #2 diesel and was used as received. 2-butoxyethanol (ethyleneglycol butyl ether) was purchased from Fischer Scientific Company and was used as received.

Example 1

In this first example, bitumen removal from tar sands using 2-butoxyethanol (ethyleneglycol butyl ether) was explored. The tar sands were subjected to a number of bitumen removal treatments and evaluations. In Treatment 1, 20 g of tar sands (obtained from Canada) was contacted with 25 ml of 2-butoxyethanol, and stirred for about 30 minutes. The liquid turned quickly to black and the tar sands sample and the tar sands lumps broke up into sand particles. The mixture was then filtered using API WL method (API RP-13B) and the solids were dried in an oven at 220° F. The sample was then treated again, Treatment 2, by mixing with an additional 20 ml of butoxyethanol, stirred for 30 minutes and filtered. Again, the solids were dried in an oven at 220° F. Some of the remaining sands residue was saved (Sample 1A), and the rest were then treated a third time, Treatment 3, by drying to remove the low volatility components remaining in the sands. Finally, the sample was placed in an oven at 105° C. for one hour with 20 inches Hg vacuum, Treatment 4. The sands residue (Sample 1B) was then weighed twice and averaged. The treatments and their results are summarized in Table 1.

TABLE 1 Treatment No. Treatment Description Treatment Values Weight Loss 1 Add 25 ml butoxyethanol to 20 g tar Solvent turned black  9.85% sands on contact with tar sands stir about 30 minutes, filtered, Pre-treatment Weight = 20 g dried at 220° F. Post Treatment Weight = 18.03 g 2 Add 20 ml butoxyethanol, Pre-treatment Weight = 16.2 g  4.51% stir about 30 minutes, Post Treatment Weight = 15.47 g heated to 220° F. 3 Vacuum oven (20 in Hg) Drying oven 0.263% heated from 20 to 97° C. 4 Vacuum oven Drying oven 0.543% heated to 105° C. for1 hr.

The results demonstrate the ability to remove bitumen from tar sands using a series of chemical and heat treatments. However, even after chemically treating the tar sands (Treatments 1 and 2) and heat treating (Treatment 3), additional volatile components remained as evidenced by a weight loss of 0.543% upon a final heat treatment, Treatment 4.

Additionally as a comparative study, 4 g of sand residue after Treatment 2 from above was mixed with 20 ml of SX-12 and the mixture was stirred for 30 minutes. The stirring was stopped and the sand was allowed to settle. The SX-12 layer has a light yellow color indicating minimal extraction of bitumen from the tar sand. In contrast, the addition of 5 ml butoxyethanol followed by stirring for 5 minutes resulted in a dark liquid phase. Therefore, the addition of the butoxyethanol to the SX-12 resulted in a more effective extraction of the tar sand than the SX-12 alone.

Example 2

As a control experiment, a new 20 g sample of the tar sand bitumen was heated to 950° C. The loss on ignition of this sample was 11.66 wt %.

TABLE 2 Treatment Treatment Description Values Weight Loss control Heated to 950° C. Ignition 11.66%

Example 3

3 sets of quantitative and comparative experiments were performed. 20 g of a tar sands sample was placed in a beaker and contacted with 15 ml of butoxyethanol and 10 ml of SX-12, filtered using API WL method, dried in an oven at 220° F. and weighed (Sample 5). Sample 5 was then divided into 3 samples, 5A, 5B and 5C.

Sample 5B was prepared by mixing 6.0 g of Sample 5 and 8 ml of butoxyethanol. The sample was stirred for one hour with a magnetic stirrer. The sand was allowed to settle for two minutes and the liquid was decanted. The liquid phase was colored, but not darkly. The solids were dried to a constant weight in an oven at 220° F. The weight of the solids was 5.98 g (Sample 5B).

Sample 5C was prepared by mixing 6.0 g of Sample 5, 6 ml of butoxyethanol, and 2 ml of SX-12. The sample was stirred for one hour with a magnetic stirrer. The sand was allowed to settle and the liquid was decanted. The liquid phase was colored, but not darkly. The solids were dried to constant weight in an oven at 220° F. The weight of the solids was 5.98 g (Sample 5B).

Samples 5A, 5B and 5C were then heated to 950° C. to test for the loss on ignition. For Sample 5A, a 0.061 g loss on ignition occurred. For Sample 5B-2, a 0.027 g loss on ignition occurred. For Sample 5C-2, a 0.026 g loss on ignition occurred. The results are summarized in Table 3.

TABLE 3 Treatment No. Treatment Description Treatment Values Weight Loss 5 Add 15 ml Pre-treatment Weight = 20 g  2.33 g butoxyethanol, Post Treatment Weight = 17.67 g Add 10 ml SX-12, stir about 30 minutes, dried at 220° F. 5A Heated to 950° C. Loss on Ignition 0.061 g Pre-treatment Weight = 4.842 g Post Treatment Weight = 4.781 g 5B Add 8 ml Pre-treatment Weight = 6 g  0.02 g butoxyethanol, Post Treatment Weight = 5.98 g stir about 60 minutes, heated to 220° F. 5B-2 Heated to 950° C. Loss on Ignition 0.027 g Pre-treatment Weight = 5.920 g Post Treatment Weight = 15.893 g 5C Add 6 ml butoxyethanol, Pre-treatment Weight = 6.00 g  0.02 g Add 2 ml SX-12 Post Treatment Weight = 5.98 g Stir about 60 minutes, Heated to 220° F. 5C-2 Heated to 950° C. Loss on Ignition 0.026 g Pre-treatment Weight = 5.898 g Post Treatment Weight = 5.872 g

The results demonstrate that samples subjected to more than one contact with butoxyethanol or a mixture of butoxyethanol and SX-12 showed a higher % bitumen recovery when compared to the samples contacted only once with these solvents.

Example 4

A comparative study between diesel oil #2 and SX-12 to remove bitumen from tar sands was investigated. The detailed procedure and results are tabulated in Table 4. 20.0 g of tar sand was placed in a beaker. 25 ml of diesel oil #2 was added to tar sands and mixed for 30 minutes with a magnetic stir bar. The stir bar was carefully removed and the mixture was allowed to stand for about 5 minutes. The liquid was decanted and the solids were transferred into the API WL cell containing a preweighed filter paper. The solids were spread out on the filter paper and the liquid was squeezed out of the solids. The filter paper was kept in an oven at 220° F. until dry. The beaker with a very few solid residue was also dried in the oven at 220° F. The dry solid particles were transferred on to the filter paper before weighing the dried solids and the filter paper. The weight of the sand residue, designated Sample 6, was 17.86 g.

A similar experiment was carried out using SX-12 instead of diesel oil #2.20 g of tar sands extracted with 25 ml of SX-12 and the residue was dried. The recovered sand residue was weighed at 17.7 g. It was noted that the sand residue extracted with SX-12 dried much faster than when using diesel oil #2. The details and results for both Samples 6 and 7 are tabulated in Table 4.

TABLE 4 Treatment No. Treatment Description Treatment Values Weight Loss 6 Add 25 ml diesel oil #2, stir about 30 Pre-treatment Weight = 20 g 2.14 g minutes, Post Treatment Weight = 17.86 g heated to 220° F. for about 24 hour 7 Add 25 ml SX-12, stir about 30 Pre-treatment Weight = 20 g 2.30 g minutes, Post Treatment Weight = 17.70 g heated to 220° F. for about 24 hour

Example 5

A comparative study between SX-12 and butoxyethanol to remove bitumen from tar sands was investigated. The detailed procedure and results are tabulated in Tables 5.

5 g of the dried residue of Sample 7 was placed in a beaker. 5 ml of SX-12 was added to the beaker and the mixture was stirred for 30 minutes. The sample was worked up following the procedure of Example 4. The dried sand, designated Sample 8, was weighed at 4.92 g.

Similarly, 5 g of the dried residue from Sample 7 was placed in another beaker. 5 ml of butoxyethanol was added to the beaker and the mixture was stirred for 30 minutes. The sample was worked up following the procedure of Example 4. The dried sand, designated Sample 9, was weighed at 4.90 g and the results are summarized in Table 5.

TABLE 5 Treatment No. Treatment Description Treatment Values Weight Loss 8 Add 5 ml SX-12, stir about 30 Pre-treatment Weight = 5 g 0.08 g minutes, Post Treatment Weight = 4.92 g heated to 220° F. for about 24 hours 9 Add 5 ml butoxyethanol, stir about Pre-treatment Weight = 5 g 0.10 g 30 minutes, Post Treatment Weight = 4.90 g heated to 220° F. for about 24 hours

Example 6

The effect of the ratio of butoxyethanol to diesel oil #2 to remove bitumen from tar sands was investigated. The detailed procedure and results are tabulated in Table 6. 20.0 g of tar sand was placed in a beaker. 20 ml of diesel oil #2 and 5 ml of butoxyethanol were added to the beaker. The mixture was stirred for 30 minutes with a magnetic stir bar. The mixture was then allowed to stand for 5 minutes and the liquid was decanted. The solids were collected on a filter paper and dried at 220° F. The sand residue, designated Sample 10, was weighed at 17.65 g.

In a separate experiment, 20.0 g of tar sand was placed in another beaker. 5 ml of diesel oil #2 and 20 ml of butoxyethanol were added to the beaker. The mixture was stirred for 30 minutes with a magnetic stir bar. The mixture was allowed to stand for 5 minutes and the liquid was decanted. The solids were collected on a filter paper and dried at 220° F. The sand residue, designated Sample 11, was weighed at 17.51 g. The details of both experiments were tabulated in Table 6. As shown in Table 6, higher ratio of butoxyethanol to diesel oil #2 was more effective at removing bitumen from tar sands.

TABLE 6 Treatment No. Treatment Description Treatment Values Weight Loss 10 Add 20 ml diesel oil #2 and 5 ml Pre-treatment Weight = 20 g 2.35 g butoxyethanol, Post Treatment Weight = 17.65 g stir about 30 minutes, heated to 220° F. 11 Add 5 ml diesel oil #2 and 20 ml Pre-treatment Weight = 20 g 2.49 g butoxyethanol, Post Treatment Weight = 17.51 g stir about 30 minutes, heated to 220° F.

While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R_(L), and an upper limit, R_(U), is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R_(L)+k*(R_(U)−R_(L)), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . 50 percent, 51 percent, 52 percent, . . . 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are a further description and are an addition to the embodiments of the present invention. The discussion of a reference in the Description of Related Art is not an admission that it is prior art to the present invention, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural or other details supplementary to those set forth herein. 

1. A method of removing bitumen from tar sands comprising: contacting the tar sands with a first mixture comprising a petroleum distillate and an oxygenated solvent, and recovering a second mixture comprising (a) at least a portion of the petroleum distillate and oxygenated solvent from the first mixture, (b) bitumen and (c) sand having a reduced amount of bitumen.
 2. The method of claim 1 wherein the bitumen has an API gravity of equal to or less than about 10°.
 3. The method of claim 1 wherein the bitumen has a viscosity of equal to or greater than about 0.2 Pa·S.
 4. The method of claim 1 wherein the petroleum distillate comprises diesel.
 5. The method of claim 1 wherein the petroleum distillate is present in the first mixture in an amount of from about 2% to about 90%.
 6. The method of claim 1 wherein the oxygenated solvent comprises a glycol ether.
 7. The method of claim 6 wherein the glycol ether comprises ethylene glycol monoalkyl ether, ethylene glycol dialkyl ether, diethylene glycol butyl ether, diethylene glycol ethyl ether, ethylene glycol monobutyl ether, combinations thereof.
 8. The method of claim 1 wherein the oxygenated solvent is present in the first mixture in an amount of from about 10% to about 98%.
 9. The method of claim 1 wherein the first mixture further comprises a surfactant.
 10. The method of claim 9 wherein the surfactant comprises an alkyl polyglycoside.
 11. The method of claim 9 wherein the surfactant is present in the first mixture in an amount of from about 0.01% to about 1%.
 12. The method of claim 1 wherein the percent recovery of the bitumen from the tar sands is equal to or greater than about 50% by weight.
 13. The method of claim 1 wherein the contacting occurs via a counter current flow of the tar sands and the first mixture.
 14. The method of claim 1 wherein the contacting occurs via filtration of the first mixture through the tar sands.
 15. The method of claim 14 wherein the filtration further comprises passing the second mixture through a membrane.
 16. The method of claim 1 further comprising separating the bitumen from the petroleum distillate and the oxygenated solvent in the second mixture.
 17. The method of claim 16 further comprising converting at least a portion of the bitumen to a lighter petroleum product.
 18. The method of claim 17 further comprising recycling all or a portion of the lighter petroleum product to the first mixture.
 19. The method of claim 16 further comprising recycling all or a portion of the petroleum distillate and oxygenated solvent to the first mixture.
 20. The method of claim 1 further comprising scrubbing the recovered sand.
 21. The method of claim 20 further comprising contacting the scrubbed sand with additional solvent. 